impl Solution {
    pub fn busy_student(start_time: Vec<i32>, end_time: Vec<i32>, query_time: i32) -> i32 {
        return start_time.iter().zip(end_time.iter()).fold(0, |mut acc,(start,end)|{
            if query_time>=*start&&query_time<=*end{
                acc+=1;
            }
            acc
        });
    }
}